FW: RE: [MR] Metalcasting from a positive master - expertise needed

[Robert Rich]

----- Original Message ----- 
From: Robert Rich 
To: Gorm of Berra
Sent: 2/28/2005 2:26:12 PM 
Subject: RE: [MR] Metalcasting from a positive master - expertise needed


Gorm,

Quick and Dirty ...... Since you have an original master, and you are looking to make low temperature metal casts.  I believe you wanted to cast in pewter?
You can do this a few ways ...

1) Go to a hobby shop and inquire about low-temperature casting mold materials.  There is a silicon rubber mold making kit that is readily available that you can used to make your mold from the original positive image and then cast the pewter directly into the rubber mold.  The mold material is heat resistant and is good for a hundred or more casts. Unfortunately the name of this product eludes me  ("quick-cast" perhaps?).  Two types of kits available.  One runs about $40, the other is a grander version of the same thing $80.

2) Through a jewelry supply catalog, or online, you can purchase "Ditto", which is also a rubber based mold making kit, which also can have the metal poured directly into it.  The rubber can take heat up to 1000 degrees F.  Price ???  This product is exceptional and can create a mold lasting for a couple of hundred casts.

3) You can use Bondo.  A) fill a small box 1/2 full with Bondo, and after it sets up, cover this with a fine layer of talcum powder.  Lay your piece on its back on top of the Bondo, carefully powder the face of the piece.  Pour a second layer of Bondo into the box to fill it up.  You want to be very careful not to create any air bubbles on the face of the piece to be duplicated.  After the Bondo has set ... tear away the box.  Gently separate the two sides.  Gently separate your original from the mold.  ON THE BACK plate carve your gate (the channel where the metal will actually fill the void created by your original).  The void is connected by the gate to the reservoir, which is a conical (funnel shaped) region you will also cut out of the bondo.    The metal is poured into the funnel shaped reservoir, passes through the gate, and flows into the void of your image.  If air bubbles or air pockets become an issue during casting .... you can cut hatch marks to give the air somewhere to go across the back plate.  In most cases, the air can escape through the joint of the two plates, while the surface tension of the molten metal prevents it from doing the same.

When you want to learn how to do it in slate ... much better than soapstone ... Look me up.

Master Brendan Brisbane 
Late of AEthelmearc, but new to you.